It seems like you don't check AQI alerts in your area, so you probably did not shut your windows/doors in advance or run air filter indoors, so the exposure you

It seems like you don't check AQI alerts in your area, so you probably did not shut your windows/doors in advance or run air filter indoors, so the exposure you get on a single walk is not as big as what accumulated in your home. That stuff you breathe day in day out and in your sleep. So portable monitor in my view is overkill, I just check AQI in the area and close windows and run air filter indoors and don't cycle when it's bad. But if it's a really convenient monitor I'd not mind it! In my experience accurate monitors are not small and not cheap though...